Electron tube for indicating symbols, letters, numerals, and the like



Aug. 17, 1965 J. WEIDEL ETAL 392919634 ELECTRON TUBE FOR INDICATING SYMBOLS, LETTERS, NUMERALS, AND THE LIKE Filed June 11, 1962 2 Sheets-Sheet 1 IN VENTORS L/OACH/M WE/OEL WERNER BAUER A [TORNEY 2 Sheets-Sheet 2 Aug. 17, 1965 J. WEIDEL ETAL ELECTRON TUBE FOR INDICATING SYMBOLS LETTERS, NUMERALS, AND THE LIKE Flled June 11, 1962 INVENTORS JOA CHI/7 WE/DEL ATTORNEY United States Patent 3,20Ld34 ELECTRGN TUBE F92 ENDECATING SYMBQLS, LETTEPS, NUMERAl-S, AND THE LIKE Joachim Weidel, Am Feuchter llruchlein, and Werner Bauer, Bonn-Duisdorf, Finlrenhot, Germany, assignors to international Standard Electric Corporation, New Yorh, N.Y., a corporation of Delaware Filed done 11, 1962, Ser. No. 261,347 Claims priority, application Germany, June 16, 1951, St 17,961 Claims. (Cl. Elli-N95) The invention refers to an electron tube with which symbols, letters, numerals and the like can be indicated visual form.

The application of voltage trains precisely defined in time, slope and magnitude to the deflecting-plate pairs of a conventional cathode-ray tube, as used in oscillographs to write numerals and letters and in doing so indicating them visually, is already known to the art. Understandably, this entails application of a considerable number of circuits.

Also familiar are the so-called counter tubes, in which the position of a luminous dot on the cathode-ray tubes envelope wall is assigned a given number imprinted on the envelope wall. T he drawback here is that the person taking the reading must first make the assignment, that is, the numeral cannot be read otf directly as a luminous symbol.

Glow indicator tubes eliminate this drawback by having cathodes, shaped to represent the numerals, face a single anode and when the proper voltage is applied between cathode and anode, the cathodes edges become luminous and thus indicate the numeral, visually. The cathodes are arranged in line in the form of thin wire bent to shape the numerals, causing the inoperative cathodes to cast shadows that create considerable undesirable parallax, which makes it extremely difficult to read the nu merals from the side. The major drawback of these glow indicator tubes, however, is to be found in the gas content, which dissipates slowly during tube operation due to the unavoidable getter effect, thus causing both starting voltage and working voltage to rise, with the result that the life of the tube is relatively short, at best a few thousand hours.

An electron tube for indicating symbols, letters, numerals and the like eliminates the drawbacks described by providing in accordance with the invention a space charge producing cathode and anodes, partially or totally coated with a fluorescent substance, that conform to the symbols or symbol portions to be reproduced and by applying positive voltage in each instance only to those coated electrodes that represent the symbols or symbol portions that are to be reproduced at that moment.

Furthermore, the electron tube for indicating symbols, letters and numerals according to the invention is a highvacuum tube, with a life that can easily last more than ten times that of a glow indicator tube.

In contrast to the so-called counter tube, the instant tube allows depicting the digits of a decade in the same location, but without the involved circuitry required in operating an oscillograph tube and without the drawback of parallax associated with glow indicator tubes.

It is therefore the primary object of the present invention to provide an improved simplified display tube.

The invention will now be explained with the aid of the embodiments shown in the drawings, which contain only those parts necessary to understand the function of the arrangement. Electrode mounting supports, connections and other components are similar to those in conventional electron tubes and are not shown in detail.

FIG. 1 shows the basic elements of the tube;

dfillllfiii l Patented Aug. 11?, 1955 PEG. 2 shows the anode display configuration; and

FIGS. 3 and 4 show other embodiments of the invention.

As shown in FIG. 1, cathode 2 and anode arrangement 4 are located in tube container 1. Here a grid 3 is also inserted between the cathode and the anodes, said grid being preferably at cathode potential and tending to form an electron space-charge cloud or flood beam about the same size as the entire surface areas of anodes 4. The grid controls the electrons by permitting emission from only the areas wherein the electric field from the positive anode penetrates the grid.

FIG. 2 is a front view of the anode arrangement. In the embodiment according to FIG. 1, a transparent and heataproof pane, of insulative glass or mica for example, is coated in known fashion with a transparent conductive layer, of metal oxide for example, and divided into a plurality of separate conductive areas by etching, sandblasting or tracing lines 7, which subdivide the conductive layer, with contacts 5 being attached to individual said conductive areas. These conductive layers face the cathode and in accordance with FIG. '2 have portions covered with a luminous or fluorescent substance 6, ZnO for example, to form segments of a figure or numeral 8. Of course, in place of a special anode base, the tubes vessel itself may serve the purpose, with the individual anodes attachment to it as transparent conductive layers and the fluorescent substance then applied thereto.

Fluorescent substance 6 applied to the individual anodes now glows at the section where the proper transparent conducting anode is connected to the positive pole of a voltage source switched in the circuit between cathode and anode. That voltage may be taken, unfiltered for example, from the terminals across a small dry rectifier or direct voltage source. In FIG. 2, when the proper contacts 5 are connected to the (positive) pole, as indicated by the shading, the number 3 appears. The di its G 9 are produced in similar fashion. The external switching and selection circuitry applying voltage to particular portions may be arranged in any suitable configuration known in the art. A circuit arrangement such as described by E. A. Sack, on pp. 113-118 of the March 1958 Transactions of the American Institute of Electrical Engineers, vol. 77, Part *I, would be applicable. Typical voltages applied to the electrodes may be from to +300 volts at the anode, +5 to 25 volts at the grid, with the cathode at ground potential.

One special advantage lies in the fact that all numerals appear in the same location and in the same plane, so that shadow and scatter effects cannot occur. Of course, it is also possible to design the individual segments of the numeral 8 as pins or thin plates and to cover them with a fluorescent substance in known fashion, by electric cataphoresis for example, in which case the numeral 8 then hangs cantilevered at the lead wires of the anodes and requires no support.

Another form of the invention is an arrangement wherein the anodes are not mounted in one plane but, as in the case of a glow indicator tube, are saggered one behind the other.

At times it may also be advisable to arrange the anode support in accordance with FIG. 3. In that case the insulating base and the anodes attached thereto need not be transparent. Here, the electrons emanating from cathode 2, which is optically shielded by radiation pr otective sheet 3, fall at an angle onto the anode support whose luminescent layer faces the viewer.

It is frequently simpler, instead of applying the fluorescent substance in the shape of the symbols, here for eX- ample to indicate the tens digits in the form of a figure 8, to cover the entire anode support with a fluorescent sub stance and to mask it with a shield having cutouts, as represented in FIG. 2 by area 6. Such a shield may be arranged either in front or behind the anodes and, in accordance with FIG. 1, may serve as grid 3. i

In another embodiment of the invention shown in FIG. 4, the design of the anode support is round and it is arranged vertically to the tube vessels axis, in which case the luminescent coating preferably faces thefiatly designed light reflecting onto the photocathode produces more elecing separate adjacent segments disposed in an area in substantially a common plane, each anode including a conductive layer having predetermined portions coated with a fluorescent substance inthe form of a symbol portion, means applying voltage to selected anodes, and a grid disposed between the cathode and anodes, said grid forming the space-charge to correspond to the size of said area of said anodes and permitting emission to only said selected anodes causing said fluorescent portions thereof to glow and together form a complete symbol.

2. An electron tube display device according to claim 1, wherein the anodes are formed on a common insula- V tive plate, the conductive layers being divided into respectrous and by means of optical feedback the indication reaches maximum brightness.

' In the embodiments described, emphasis was placed on displaying a pattern in the form of digits; of course, letters, Roman numerals or any other predetermined .symbols can be indicated, if the proper number of anodes and the proper shape of the luminescent coating or of the mask are provided. These embodiments are merely exemplary and are not to limit the scope of the invention as defined in the appended claims.

We claim:

1. An electron tube display device comprising a spacecharge producing cathode, a plurality of anodes presentt-ive separate segments.

3; An electron tube display device according to claim 2, wherein the conductive layers are transparent.

4. An electron tube display device according to claim 3, wherein the insulator is transparent.

'5. An electron tube display device according to claim 1, wherein a photocathode produces the space-charge.

References Cited by the Examiner UNITED STATES PATENTS 2,244,245 6/ 41 Ehrenger-b 313-92 2,891,185 6/59 Peterson et al 313109.5 2,957,098 10/60 Bernstein 3l3-109.5 X 3,082,341 3/63 Balaskovic 3151 DAVID J. GALVIN, Primary Examiner. GEORGE N. WESTBY, Examiner. 

1. AN ELECTRON TUBE DISPLAY DEVICE COMPRISING A SPACECHARGE PRODUCING CATHODE, A PLURALITY OF ANODES PRESENTING SEPARATE ADJACENT SEGMENTS DISPOSED IN AN AREA IN SUBSTANTIA6LY A COMMON PLANE, EACH ANODE INCLUDING A CONDUCTIVE LAYER HAVING PREDETERMINED PORTIONS COATED WITH A FLUORESCENT SUBSTANCE IN THE FORM OF AW SYMBOL PORTION, MEANS APPLYING VOLTAGE TO SELECTED ANODES, AND A GRID DISPOSED BETWEEN THE CATHODE AND ANODES, SAID GRID FORMING THE SPACE-CHARGE TO CORRESPOND TO THE SIZE OF SAID AREA OF SAID ANODE AND PERMITTING EMISSION TO ONLY SAID SELECTED ANODES CAUSING SAID FLUORESCENT PORTIONS THEREOF TO GLOW AND TOGETHER FORM A COMPLETE SYMBOL. 